My African Bush Daisy Is Wilting & Dying

Prized for their golden flowers and silvery foliage, African bush daisies (Gamolepis chrysanthemoides) are widely grown in ornamental landscaping within U.S. Department of Agriculture plant hardiness zones 8 to 11. Few diseases or pests trouble them, although they are susceptible to nematode infestations. Nematodes cause several symptoms in African bush daisies, including profound wilting and plant failure. These infestations are difficult to effectively treat, so it's best to prevent them from taking hold in the first place.

Nematode Symptoms

Nematodes are insidious pests, often manifesting symptoms in the daisies that mimic those of other infections or diseases. One of the most common symptoms is wilting or drooping growth during hot weather, even when proper irrigation is provided, although you'll also see yellowing foliage and an overall loss of vigor in affected plants. The only symptom unique to nematode infections is the formation of galls, or bulbous growths, on the roots where the nematodes take hold. It's not visible on the stems or leaves, and can only be seen if you dig up the plant and examine the roots.

Nematode Prevention

No effective treatment exists for nematode infestations, so prevention is best. A planting site where nematodes have previously been should be solarized, or heat treated, to temporarily reduce nematode populations in the top 1 foot of soil. Weed and till the bed in midsummer, and then cover the soil with clear polyurethane sheeting. Leave the plastic in place for four to six weeks to trap heat on the soil surface. If possible, leave an infested planting site fallow or grow nematode-resistant plant varieties for three to five years to decrease the number of nematodes in the soil before planting African bush daisies.

Palliative Care

African bush daisies will survive a nematode infestation better if you provide palliative care. Give them 1 inch of water weekly and feed them monthly with general purpose fertilizer, following label instructions, to bolster root growth -- this will help the plants deal with stress. A thick layer of mulch around the base of the plant shields the roots and also helps guard against moisture-related stress, although it must be replaced yearly to keep pests at bay. Any dead stem or foliage growth should be pruned away to improve the plant's appearance and discourage insect colonies, but you must use freshly cleaned shears to prevent fungal or bacterial infections that may further weaken the African bush daisy.

Other Potential Causes

Wilting and death in African bush daisies is typically caused by nematodes, although there are other, more minor potential causes. Poor growing conditions or insufficient care may also cause wilting, but typically less severe than during a nematode infestation. Grow African bush daisies in a sunny bed with porous, fast-draining soil and avoid heavily shaded areas with heavy, clay-based soil. Adjust watering according to the weather, with more water during heat or drought and none during wet weather. Salt spray causes severe stress and damage to African bush daisies, so plant them in a sheltered spot when cultivating them in coastal areas.